Effect of social capital, social support and social network formation on the quality of life of American adults during COVID-19

This study aims to evaluate the effect of social capital (SC), social support (SS), and social network formation (SNF) on the quality of life of American adults during COVID-19. Using a probability sample of American adults aged 49+, 2370 respondents were selected from the National Social Life Health and Aging Project (NSHAP) dataset for analysis using an integrated partial least squares based on structural equation modeling (PLS-SEM)-K-fold cross-validation approach. The analysis showed that social capital assessed using civic engagement, social cohesion, socioeconomic status (SES), social support, and social network formation were significantly and positively associated with American adults’ quality of life during the COVID-19 pandemic. Furthermore, the results showed that using the PLS-SEM and K-fold cross-validation approach produced a medium predictive power of the overall model, confirming the importance of SC, SS, and SNF in predicting quality of life-outcomes. These findings suggest that efforts to promote the well-being of American adults, especially older adults, during the pandemic should focus on strengthening social capital, social support and social network formation.

Since the outbreak of COVID-19, public health officials and other auxiliary institutions have implemented lockdowns and other public health measures to prevent the spread of the virus 1 .These measures aimed to discourage large gatherings and non-essential travel and encourage staying home.Massive lockdowns meant that movement was restricted, altering people's living situations physically and socially, which presented unique issues of social isolation and a lack of connection because they were physically cut off from family and friends.
In the United States, although efforts to monitor and contain the spread of COVID-19 have received substantial national attention, literature has painted gloomy pictures of the devastating effect COVID-19 has had on individuals' social and psychological well-being 2 .The increase of COVID-19 infections and re-infections, coupled with the mutation of the virus strain and physical distancing regulations, have increased social isolation and loneliness, negatively impacting the health and well-being of many American adults, particularly, older adults, a population that is highly susceptible to social isolation.A study by Pierce et al., 2020 has documented the substantial mental health toll of the COVID-19 pandemic, exacerbated by social isolation and the disruption of social networks 3 As a critical social determinant of health, social capital plays a protective role in the quality of life, both physical and mental health, of adults, primarily the elderly 4,5 .Researchers, over the years, have classified social capital broadly into three important aspects: civic engagement, economic connectedness, and social cohesion.Others have also extended the categorization of social capital to encompass social networks and support 4,6 .Civic engagement refers to a person's level of involvement in their communities and their rate of volunteering and supporting other social causes 7 , while economic connectedness refers to a person's connection based on income classification or socioeconomic status 8 .According to Corvo and De Caro, 2019 9 , social cohesiveness associated with: lower self-rated health 34 and a worse condition of the mental and physical components of health-related quality of life in women 35,36 .
Although there is a wealth of research on the individual association between social capital, support, and mental and physical health, few studies have examined the combined effect of these factors, especially during the COVID-19 pandemic.The pandemic disrupted traditional avenues for social connection, leaving many adults, especially older adults, to rely on technology to access social capital, networks, and support.This raises the novel question of how effective technology can be in providing these essential resources and how that translates into impacting the quality of life of adult Americans.In addition, how the involvement and advocacy in racial discrimination and inequity campaigns in America can enhance civic engagement and improve the overall quality of life of adults during a pandemic, to a large extent remains unknown.Thus, to address these gaps, this study relied on a nationally representative cross-sectional sample, to investigate the impact of social capital, network, and social support on the quality of life of American adults and older adults during COVID-19.The findings from this study could be used to develop interventions to promote social capital, social support, and social network formation and improve the quality of life of adults and older adults during the pandemic and beyond.

Sample, sampling procedure, and data collection
Using a probability sample of American adults and older adults aged 49+, 2370 respondents were selected from the National Social Life Health and Aging Project (NSHAP) dataset 37 , with African-Americans and Hispanics sampled at a higher rate.Questionnaires for the study were distributed via a web survey, a phone interview, or a paper-and-pencil mail-back instrument.Participants were initially interviewed in Round 3 (R3) (2015-2016), and a supplementary interview was conducted during the COVID-19 pandemic between September 14, 2020, and January 27, 2021.

Outcome variable
Quality of life during COVID-19 (CoQoL).To evaluate the quality of life of respondents in COVID-19, this study assessed both the self-reported mental and physical health of adults and older adults.Since several studies on evaluating health-related quality of life have broadly categorized two key components, that is, mental health and physical health 38,39 , this study also relied on these two groupings.Self-rated mental health was measured by asking respondents to rate their overall mental health on a 5-Likert scale, with 5 representing excellent, three as "good," and one as "poor" mental health.Additionally, respondents were asked to report their physical health on a scale of 1 to 5, with 1 depicting poor physical health and five as "excellent" physical health.

Independent variables
Social capital (SC).Civic engagement (CE): Civic engagement, or participation in activities that contribute to a community's well-being 40 , can positively impact the quality of life of adults and older adults during the COVID-19 pandemic.Civic engagement can take many forms, such as volunteering, participating in community organizations, or advocating for issues of importance to the community.For older adults, civic engagement can provide a sense of purpose and meaning, as well as a sense of belonging and connection to the community.It can also have physical and mental health benefits [41][42][43] , providing opportunities for social interaction and helping reduce feelings of loneliness and isolation.During the COVID-19 pandemic, civic engagement may need to be adapted to comply with social distancing and other public health measures.However, there are still many ways for individuals to engage in their communities, such as through virtual volunteering or participating in online community events.Overall, the benefits of civic engagement for adults and older adults during the COVID-19 pandemic may include improved mental and physical health, a sense of belonging and connection to the community, and a sense of purpose and meaning.
To assess civic engagement, respondents were asked to determine the frequency of contacting representatives, signing petitions, or donating to address racial justice issues, such as the death of George Floyd or Black Lives Matter (BLM).Respondents were also asked to provide how often they had conversations with family or friends about race and racial justice, posted or shared content about racial justice on social media, or took other action regarding racial justice or BLM, using a 3-Likert scale with 0 as "never, " 1 as "sometimes" and two as "often." This study, therefore, posits that: H1 CE, as a component of SC, has a significantly positive impact on the CoQoL of adults and older adults during COVID-19.

Social cohesion (SCoh):
Social cohesion, or the sense of belonging and connection within a community, can positively affect the quality of life of adults during the COVID-19 pandemic.Social cohesion can be promoted through volunteering, participating in community events, and interacting with neighbors and other community members.For older adults, social cohesion can provide a sense of belonging and purpose and help reduce feelings of loneliness and isolation.It can also benefit physical and mental health, as social connections and relationships are essential to overall well-being.During the COVID-19 pandemic, social cohesion may be challenged by the need to maintain physical distance and limit in-person interactions.However, there are still many ways for adults, especially older ones, to keep social connections, such as through virtual social events or regular phone or video calls with loved ones.Overall, the benefits of social cohesion for adults during the COVID-19 pandemic may include improved mental and physical health, a sense of belonging and connection to the community, and a Vol:.(1234567890 Socioeconomic status (SES): Socioeconomic status (SES) can significantly impact the quality of life of adults during the COVID-19 pandemic.Studies have found education and income to be among the key predictors of health among older adults 44,45 .More significantly, these studies have identified a strong positive association between higher education and better cognition [44][45][46] .However, adults and older adults with lower SES may be more vulnerable to the adverse effects of the pandemic, as they may have less access to healthcare, financial resources, and social support.Individuals, especially older adults with lower SES, may be more likely to experience economic insecurity and material hardship during the pandemic, as they may have limited savings or other resources to fall back on in the event of a loss of income.They may also need more access to quality healthcare, making it more challenging to manage chronic conditions or access necessary medical treatment.In addition, adults and older adults with lower SES may be more vulnerable to social isolation and loneliness, as they may have fewer social connections and support networks to rely on during the pandemic.This can have adverse effects on mental health and overall well-being.Overall, the impact of SES on the quality of life of adults and older adults during the COVID-19 pandemic may vary.Still, those with lower SES may be more vulnerable to negative impacts such as financial insecurity, limited access to healthcare, and social isolation.
Socioeconomic status was evaluated using the income classification (how well an individual's income met their basic expenses) and the educational level.Income was categorized into low, lower, middle, and upper income.Similarly, education was grouped into four classes: less than high school, high school or equivalence, vocational/ associate/some college, and bachelor's degree or higher.Including these indicators is relevant in appreciating the role of SES on the quality of life of adults and older adults during COVID-19.This study, therefore, hypothesized that: H3 SES, as a component of SC, has a significantly positive impact on the CoQoL of adults and older adults during COVID-19.
Social support (SS).This study evaluated both tangible and emotional support received by individuals during the pandemic to assess social support.Tangible support was measured by determining the level of help an individual received in performing everyday tasks.In contrast, emotional support was measured by evaluating whether an individual received advice, comfort, love, or other forms of emotional support.Based on these questions, this study posits that: H4 SS has a significantly positive impact on the CoQoL of adults and older adults during COVID-19.
Social network formation (SNF).To determine the extent to which social network formation impacts the quality of life of adults and older adults, this study examined the frequency of contact (FoC) with family and friends and the relationship quality (RQ).Respondents rated the quality of their relationship with their partners as better, worse, or the same as before the COVID-19 pandemic and rated their relationship happiness on a scale of 1-7 with 1, "very unhappy, " and 7, "very happy." How often respondents had phone calls and in-person visits with family was used to examine the frequency of contact during COVID-19.This study hypothesizes that: H5a RQ, as an SNF component, has a significantly positive impact on the CoQoL of adults and older adults during COVID-19.
H5b FoC, as an SNF component, has a significantly positive impact on the CoQoL of adults and older adults during COVID-19.
Based on the hypothesis developed above, a framework was developed indicating all the interactions between the variables, as shown in Fig. 1.

Statistical analysis
Due to its robust estimates and statistical power 38,47 , partial least squares (PLS) based on structural equation modeling (SEM) was employed to test and validate the hypothesized model.The choice of PLS-SEM, beyond those alluded to above, is well-suited to the research objectives of this study, which aims to investigate the impact of social capital, network, and social support on the quality of life of American adults during COVID-19.PLS-SEM is particularly well-suited for exploratory and predictive research [48][49][50][51] , where the focus is on understanding relationships between constructs and predicting outcomes [48][49][50][51] .Additionally, PLS-SEM is an appropriate choice for analyzing the cross-sectional data 49,52 as used in this study.The model's validity was determined by analyzing the measurement and structural models.
The model-building process began with data preparation.This involved cleaning the data, removing any outliers, and performing imputation for the missing values.Next, the measurement model was assessed by  53 , correlation values of redundancy analysis must be ≥ 0.70 to be considered acceptable for single-item constructs, while VIF ≥ 5 indicates probable collinearity problems, ranging between 3 and 5 as a possibility for collinearity problems and < 3 indicating no collinearity problems 53,54 .For the significance of the outer weights, t-statistics values have to be 2.576 (1% CI), 1.96 (5% CI), and 1.645 (10% CI), respectively, to be considered significant 54 .The relevance of the indicators with a significant weight is determined based on the size of the indicator weights, with larger standardized indicator values closer to + 1 (− 1), suggesting a strong relative contribution to the constructs.If a confidence interval does not contain a zero value, the weight is statistically significant, and the indicator can be kept.On the other hand, if an indicator weight's confidence interval contains 0, it implies that the weight is not statistically significant (assuming the provided significance threshold, e.g., 5%).In this case, the indicator should be eliminated from the measurement model 54 .
Once the measurement model was deemed to be satisfactory, the structural model was assessed by examining the hypothesized relationships between the constructs.The structural model was evaluated using the variance inflation factors (VIF), path coefficient (β), t-statistics, p-values, and (Q 2 predict) 54 .Model fit analysis was also performed using the Standardized Root Mean Square Residual (SRMR), discrepancy function (d_ULS and d_G), chi-square statistic, and the Normed Fit Index (NFI).SRMR < 0.08 is considered acceptable 55 , while the closer the NFI is to 1, the better the fit.NFI values above 0.9 usually represent an acceptable fit 56 .K-fold crossvalidation 57 was used to assess the model's overall predictive performance using PLSPredict 58 with ten folds and ten iterations.A number of different models were built and tested before the final model was chosen.The final model was chosen because it had the best fit for the data and the most theoretically sound relationships.The PLS-SEM analysis was performed using SmartPLS 4.0 59 .

Handling missing data
To account for the missing data in the dataset, Multivariate Imputation by Chained Equations (MICE) 60 was used.In all, five imputations (m = 5) were done in twenty iterations (maxit = 20) using the Predictive Mean Matching (pmm) technique 61 in R.

Ethical approval and consent to participate
All protocols for the NSHAP were approved by the National Opinion Research Center (NORC) at the University of Chicago (Protocol Number: 14.06.01) and carried out in accordance with the Declaration of Helsinki and other essential guidelines and ethical review regulations that applies to conducting studies involving human participants.The approval also covered all procedures through which written informed consent was obtained from each participant, including them being informed about the objective of the study, and guarantee of anonymity.Confidential records of participants' consent were maintained by NORC and thus, this current study did not include any confidential records of participants.Furthermore, informed consents for participating in the study were obtained from each participant.

Consent to participate
Informed consent was obtained from all respondents involved in the study.

Descriptive statistics
Results of the respondent's demography are shown in Table 1.Of the total respondents, 735 were aged 60-69 years.The number of females was 1318, while males were 1052.Furthermore, the most observed category for the level of education was vocational/some college/associate and the most observed category income level was middle-income level.

Evaluation of measurement model
Collinearity, outer weights, t-statistics, and p-values were used to evaluate the measurement model as shown in Table 2. Results revealed that almost all constructs had outer weights higher than 0.5, except for CE2, SCoh1, and FoC1; however, CE2 and SCoh1 were statistically significant.Furthermore, all constructs had VIF < 3 suggesting no collinearity problems.

Structural model, hypothesis testing, and robustness check
Results of the structural model are shown in Table 3 and Figure 2, respectively.
Results of the structural model revealed a statistically significant relationship between all the constructs, thus, supporting hypotheses H1, H2, H3, H4, H5a, and H5b, respectively.The summary of the fit indexes showed SRMR less than 0.08 and NFI approximately equal to 0.90, thus, suggesting model fit, as shown in Table 3.Furthermore, Q 2 predict values were greater than zero indicating the model outperformed the most naïve benchmark.At the same time, the K-fold cross-validation result for both the PLS model and LM model produced an RMSE of 0.90, suggesting the overall model had a medium predictive power.

Discussion
This study evaluated the impact of social capital, social support, and social network formation on American adults' quality of life during the COVID-19 pandemic.The study found a significant positive relationship between civic engagement, SES, and social cohesion, which were used to measure social capital and quality of life during COVID-19.These findings are consistent with previous studies that have established an association between social capital and quality of life pre-COVID-19 [62][63][64][65] .
Research has shown that adults, especially older adults who are civically engaged, tend to have better physical and mental health outcomes [41][42][43] , as well as a greater sense of purpose and meaning in their lives.Civic engagement can include, volunteering, participating in community events, and in the case of this study, supporting racial justice and equity.During the pandemic, civically engaged individuals were more likely to have access to information and resources that helped them cope with the pandemic's challenges.For example, adult and older adults involved in community organization initiatives to bridge the racial inequality gap in healthcare and other social issues were more likely to know about local resources and support available.Additionally, civically engaged individuals were more likely to be connected to their community, which can provide a sense of belonging and social support.
Social cohesion and SES significantly correlated with better quality of life during the pandemic.These findings are in line with previous studies [66][67][68] .Research has shown that older adults who live in communities with high levels of social cohesion tend to have better physical and mental health outcomes 69,70 .This is likely because social cohesion can provide adults, especially those advanced in age, with a sense of belonging and support, which can mitigate the adverse effects of stress and isolation.Socioeconomic status (SES), a measure of an individual's economic and social position in society, is also an important factor in adults' quality of life during the COVID-19 pandemic.This status can be influenced by income, education, and occupation.During the pandemic, many people lost their sources of livelihood, and for people of color, that translates into issues of food insecurity, loss of home, shelter, among other things.Research has shown that individuals from lower SES backgrounds are more likely to experience adverse physical and mental health outcomes during the pandemic 71 .This is likely because individuals from lower SES backgrounds may need more access to resources and support, making it more difficult for them to cope with the challenges of the pandemic.Thankfully, due to the introduction of many pro-poor interventions during the pandemic 72 , many people received some financial relief due to the heightened demand for social justice and equity; hence, this could explain the positive association between SES and quality of life in this study.Also, individuals had sufficient income and financial reserves pre-pandemic which they fell back on to provide for their sustenance, thus, causing a positive impact on their overall quality of life.A significant positive association was observed between social network formation assessed by the frequency of contact and the quality of relationships among older adults and their quality of life.Previous studies have shown that social network formation is positively associated with the quality of life of adults and older adults 30,73,74 .For example, a study by Berkman and Glass 30 found that older adults with more extensive and diverse social networks tended to have better physical and mental health outcomes 30 .Similarly, a study by Vos et al. 74 found that older adults who reported a higher level of social network formation were less likely to experience adverse mental health outcomes during the COVID-19 pandemic 74 .Furthermore, a study by Charles et al. 75 found that older adults who reported a higher level of relationship quality were less likely to experience adverse mental health outcomes 75 .While there is no definite evidence that social network influences the incidence of illness, it appears that it does enhance the likelihood of a favorable prognosis in the case of heart ischemia and cerebrovascular disease 76 .This is likely because social networks can provide individuals access to a broader range of resources and support, including information, resources, and practical assistance, thus positively impacting their quality of life.
Finally, a significant positive relationship was established between social support and the quality of life of adults and older adults during the pandemic in America.Research has shown that older adults with a strong social support network tend to have better physical and mental health outcomes during times of stress 73,77,78 , such as during a pandemic.This is most likely because social support can help mitigate the adverse effects of stress and isolation, which can be especially severe in older adults.This study observed that adults and older adults who had the financial means to get physical or tangible help could do so even if their immediate family members or friends could not provide them with finances.Others also alluded to the fact that their family and friends could offer emotional support to them through various technologies and social media, consequently serving as a protective factor against their stress and anxiety, leading to a better self-rated quality of life.

Conclusion
This study examined the effects of social capital, social support, and social network formation on American adults' quality of life during COVID-19.The findings of this study indicate that social capital, social support, and social network formation positively impact the quality of life of American adults during the COVID-19 pandemic.Furthermore, the findings of this study underscore the importance of taking individual and community-level factors into account when developing interventions and policies aimed at improving the well-being of Americans, particularly for older adults during the COVID-19 pandemic and beyond.At the individual level, it is imperative to encourage adults to participate in civic activities, such as volunteering, participating in community events, and supporting racial justice and equity causes.This can help individuals stay connected to their community and find purpose and meaning in their lives.Steps should also be taken to address the social and economic determinants of health, such as poverty, income inequality, and lack of access to healthcare and other essential resources, as these will help to improve the overall well-being of adults, regardless of their social status.At the community level, there is a need to promote social cohesion by building strong community ties and fostering a sense of belonging among American adults.This can be done by supporting community organizations and programs that bring people together.Furthermore, it is important to ensure that adults have access to quality healthcare and other essential services, such as food, housing, and transportation, as these will help adults to meet their basic needs and live healthy and fulfilling lives.Based on the findings of this study, we also recommend the creation of age-friendly communities that are safe, accessible, and inclusive for older adults.This can be done by making modifications to public spaces and transportation systems, and by providing programs and services that are tailored to the needs of older adults.

Limitation
Though this current study provides valuable insight into the subject matter, it is essential to note that it has some limitations that may not be generalizable to other adult populations and geographic locations.
First, the data used for this study is specific to geographical locations in the United States of America; thus, the conclusions drawn are relative to those locations.Hence, relying on this study to understand the effect of the constructs used in other jurisdictions should be done cautiously, as the situations during COVID-19 in the USA might be different in those locations.
Second, the study was conducted during the early stages of the pandemic; hence, it might not have captured the broader duration, more so as the pandemic is still active.It will therefore be essential to replicate the study in the future to examine the longer-term effects of social capital, social support, and social network formation on the quality of life of adults and older adults during the COVID-19 pandemic.
https://doi.org/10.1038/s41598-024-52820-ytesting the validity of the constructs and indicators in the model.Since the model in this study is formative, the measurement model was evaluated using convergent validity (redundancy analysis), VIF, the statistical significance of weights (t-statistics or p-values), and the relevance of indicators.According to Hair et al.
sense of purpose and meaning.Social cohesion was evaluated by how often respondents used email, texts, social media, phone calls, and video calls to connect with their family and friends since the start of COVID-19.Based on the above literature, this study posits that: H2 SCoh, a component of SC, has a significantly positive impact on the CoQoL of adults and older adults during COVID-19.

Table 3 .
Structural Model and Robustness Check.